Flexible alerting for integrated cellular and voip

ABSTRACT

An integrated cellular/Voice over IP (VoIP) telephone system including a flexible alerting system, which in response to an inbound call placed to a pilot telephone number, routes a first call leg to a cellular telephone assigned to the pilot telephone number and a second call leg to a telephone number. The telephone system includes a VoIP server configured to establish an inbound call to a VoIP client and establish an outbound call setting caller identification data corresponding to the pilot telephone number, responsive to an outbound call by the VoIP client. An outbound call from the VoIP client to the pilot telephone number is automatically routed to a voice mail system unless otherwise indicated. Based on an indication to not use a pilot telephone number for caller identification, an outbound call is established from the VoIP client to the cellular telephone, without being automatically directed to the voice mail system.

RELATED APPLICATIONS AND CROSS REFERENCES

This application is a continuation of and claims the benefit of U.S.application Ser. No. 12/240,597, filed Sep. 29, 2008, titled “FLEXIBLEALERTING FOR INTEGRATED CELLULAR AND VOIP,” the disclosure of which isentirely incorporated herein by reference.

FIELD OF THE INVENTION

The present subject matter relates to techniques enabling transparentintegration of cellular and VoIP telephone services.

BACKGROUND

As broadband IP connectivity to homes and offices has become morecommon, and the speeds of packet-switched communications equipment andthe speed of processors have increased, a variety of applications haveemerged that utilize IP packet transport as an alternative bearer forvoice communications. Generally, such applications are referred to asvoice-over-packet services, however, the common forms based on InternetProtocol (IP) are referred to as “Voice over IP” or “VoIP” services.

Additionally, cellular telephone services have grown in popularity.However, cellular telephone services are typically offered at a costexceeding wireline VoIP telephone services. Thus, when a subscriber isat the home or office, the use of a wireline VoIP is preferred in orderto reduce overall communications costs. However, without some degree ofintegration of the wireline VoIP and cellular services, a subscriber hastwo separate phone lines, phone numbers, and voice mail services. Thispresents inconvenience for those wishing to contact a subscriber, asthey must be aware of and attempt to contact the subscriber at multipletelephone number. Further, having two independent services is aninconvenience for a subscriber, as multiple voice mail systems must bechecked for messages. Additionally, for subscribers who are frequentlyaway from the home or office, the cellular service often becomes aprimary point of contact, thereby diminishing the benefit of wirelineVoIP service in the home or office.

For the sake of convenience, various approaches to cellular/wirelineVoIP integration schemes have been developed. These approaches rely onVoIP technology to provide the “glue” that integrates the cellularservice with the wireline VoIP service. Such methods require all callsto or from a subscriber's cellular phone to be “anchored” at a controlpoint in the IP network (e.g., a softswitch or feature server). Onemechanism often employed involves the use of wireless intelligentnetwork triggers. However, these triggers are often unavailable becausethey are already being used to provide the same subscribers with otherservices (e.g., call screening services, private dialing plans, etc.).Additionally, there are often restrictions on the use of certaintriggers while roaming, making them unsuitable to use for call“anchoring.”

Ultimately, none of the above approaches provide full service andfeature transparency to the cellular phone subscriber. Specifically,these services fail to provide the subscriber with all of the followingattributes, which together yield an enhanced level of cellular/wirelineVoIP integration:

-   A single number that appears as caller identification data when the    subscriber calls another party.-   A single number used by other parties to call the subscriber,    whereby both the subscriber's cellular phone and wireline VoIP would    ring, with the incoming call completing to whichever phone (cellular    or wireline VoIP) the subscriber chooses to use when answering.-   An integrated voice mail box shared by the cellular and wireline    VoIP services, and as readily accessible from the wireline VoIP    service as from the cellular service.-   If one of the phones is in use when the subscriber is alerted for    another incoming call, the subscriber has the option of accepting    the call from the idle phone, accepting the call from the phone in    use as a call waiting call, or allowing the incoming call to be sent    to the integrated voice mail box.-   No loss of service transparency while roaming.-   Maintain an existing cellular phone number, rather than require a    new shared number.-   Maintain other cellular features to which the subscriber has become    accustomed.-   Allow use of a third-party Internet Service Provider (ISP) for    broadband access over which wireline VoIP service is delivered.-   Reject calls directly placed to the wireline VoIP, so as to allow    callers only a single telephone number for contacting the    subscriber.    For calls made to a public safety answering point (PSAP), such as    911 calls in the United States, from a VoIP phone, provide caller    identification data corresponding to the wireline VoIP phone, and    allow subsequent PSAP-originated call back calls to be made.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present teachings, by way of example only, not by way of limitation.In the figures, like reference numerals refer to the same or similarelement.

FIG. 1 provides a high-level illustration of an embodiment of a systemthat may offer an integrated service of the type discussed herein.

FIG. 2 provides a high-level illustration of operations performed inplacing a call from a VoIP client to a phone on a PSTN.

FIG. 3 provides a high-level illustration of operations performed inplacing a call from a VoIP client to its related mobile station.

FIG. 4 provides a high-level illustration of operations performed inplacing a call from a VoIP client to a public safety answering point,and the reverse.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

FIG. 1 provides a high-level illustration of an embodiment of a systemthat may offer an integrated service of the type discussed herein.

Mobile Station (MS) 11 represents a subscriber's cellular phone device.Currently mobile or wireless devices on active accounts with thewireless carrier are assigned one or more numbers for deviceauthentication and related signaling purposes. Typically, a mobilestation is assigned a mobile directory number (MDN) and a mobileidentification number (MIN). The MDN is an actual telephone number. TheMIN has a telephone number format but is typically a second numberassigned to the device only for signaling purposes. At least the MIN andusually the MDN are programmed into the subscriber's mobile station, aspart of the process of provisioning the device for operation through thewireless network. Association of those numbers with the subscriber andthe subscriber's mobile station are also recorded in various databasesused for service control, billing and the like in or otherwiseassociated with the wireless network. These numbers, particularly theMDNs, are resources available to the cellular service provider on alimited basis.

A Mobile Switching Center (MSC) 21 is responsible for handling voicecalls as well as other services (such as SMS, conference calls, FAX, andcircuit switched data) as a service delivery node and sets up andreleases the end-to-end connection, handles mobility and hand-overrequirements during the call and takes care of reporting call statisticsfor charging. The MSC 21 connects with a Public Switching TelephoneNetwork (PSTN) 40. Calls routed through the MSC 21 are directed to otherMSCs (not shown herein), to special service nodes (e.g., voice mailsystems) or to external networks by way of PSTN 40. An MSC assigned toan MDN is the “Home MSC” for the MDN and the associated mobile station,although in some implementations a subscriber base may be distributedacross a plurality of MSCs, any of which may function as a “Home MSC.”

A base transceiver system (BTS) 17 included in a base station (BS) 15assigns and reassigns channels to a mobile station 11 that it serves,and monitors the signal levels to recommend hand-offs to other basestations. The network typically includes a base station controllerfunctionality (not illustrated) that controls the functions of a numberof base stations and helps to manage how calls made by each mobilestation are transferred (or handed-off) from one serving base station toanother. Each wireless network equipment vender implements this functiondifferently. Some vendors have a physical entity, which they call a BSC,while other vendors include this functionality as part of their MSCswitch.

The MSC 21 supports a Flexible Alerting (FA) feature. FA is astandardized cellular feature that allows an MDN (i.e., a cellular phonenumber) to serve as the “pilot” number for a group of telephone numbers.A mix of cellular and non-cellular numbers is allowed. The cellularphone associated with the “pilot” MDN is referred to as the pilot of thegroup, and the phones (including the pilot) associated with the numbersin the group are referred to as an “FA group.” When a call is placed tothe “pilot” MDN, the Home MSC for the pilot of the group concurrentlyroutes FA call legs to every available member of the FA group, and allof these phones are given an opportunity to answer the call. The HomeMSC connects the caller to the first FA call leg to answer, or, if noneof these legs answers, the Home MSC directs the call to voice mailsystem 26. The voice mailbox would be that associated with the pilotnumber.

Note that the above description of the handling of an incoming FA callmerely describes processing under normal circumstances. However, thesubscriber can choose to modify the handling of an incoming FA call byactivating features such as Call Forward Unconditional or CallForwarding No Answer.

Home Location Register (HLR) 39 is a database storing subscriberfeatures and settings, and has a pointer telling which MSC 16 MobileStation 11 is located in. As recognized in the art, an HLR stores foreach mobile subscriber station the subscriber's mobile directory number(MDN), the MIN, and information specifying the wireless servicessubscribed to by the mobile subscriber, such as voice service features,SMS, etc. One aspect of normal HLR processing of an incoming voice orSMS call involves translation of the MDN associated with the call intothe MIN, for use in completing the call to the mobile station 11. Foreach mobile station, the HLR also stores data identifying the currentpoint of attachment of the mobile station to the network.

Typically, wireline VoIP services utilize packet switching for theswitch fabric, and the call processing is implemented by SoftSwitchComplex (SSC) 37. The SSC 37 may be operated by the carrier or serviceprovider operating the cellular network 13, or by a separate entity,generally under an agreement with that carrier/service provider to allowthem to jointly offer the integrated service. The SSC 37 is typicallyprovided through a combination of cooperating components thatcollectively provide necessary functions including database servers,service logic application servers, and security servers media resources(e.g., conference bridges, transcoders, announcement servers).Typically, a VoIP subscriber base will be distributed across a pluralityof SSCs. SSC 37 may, but need not, conform to the architecture of the IPMultimedia Subsystem (IMS) which is the basis for much of the worldwidework to develop standards for “next generation” telecommunicationssystems. Most current VoIP SSC implementations rely on the SessionInitiation Protocol (SIP) for the signaling to set-up calls for voiceand other multimedia sessions, as standardized by the IETF. Althoughpresent integrated service is not dependent upon any specific VoIPprotocol, exemplary embodiments will be discussed with respect to SIP.

A set of phone numbers is assigned to a VoIP service provider, with thephone numbers “homed” to SSC 37, for use as “integration routingnumbers” 38, as to be detailed below. The phone numbers may come from“Office Codes” officially assigned to SSC 37 through the normalNumbering Administration process, pooled blocks assigned to SSC 37,“ported” to SSC 37, or otherwise.

A Media Gateway (MGW) 25 provides an interface between the circuit-basedcellular network, which includes MSC 21, and the IP-based VoIP network,which includes SSC 37. MGW 25 supports SIP-I (also known as SIP-T) (inaccordance with Profile C as described in ITU recommendationQ.1912.5-2004) for interworking between ISUP and SIP. Typically, aplurality of geographically dispersed MGWs is used by a cellular network13.

VoIP data is exchanged with a subscriber installation via Internet 35,which is typically delivered to a subscriber endpoint 22, such as a homeor office, by an Internet Service Provider (ISP). The ISP may be acarrier or service provider other than the cellular service provider. Atthe subscriber endpoint 22, network access is typically provided via abroadband modem 33, which may be, for example, a cable modem or adigital subscriber line (DSL) modem, a data device for communicationover fiber, a wireless network, or any other type of IP network capableof multimedia session communications. The present concepts alsoencompass arrangements that utilize wireless or fiber transport for IPpacket services. Through broadband modem 33, a subscriber is providedwith two-way IP packet communication, suitable for wireline VoIPservice.

The subscriber is provided with a Residential Gateway 23 for wirelineVoIP service. The Residential Gateway 23 connects to the subscriber'sbroadband service, whether directly to broadband modem 33 or indirectly,such as through an intermediate home router (not shown) connected to thebroadband modem 33. Residential Gateway 23 supports a VoIP client, andtypically provides one or more standard telephone adapter interfaces(with corresponding female RJ-11 connectors) so that the subscriber canconnect ordinary corded or cordless phones 12 to the Residential Gateway23. The VoIP client supported by the Residential Gateway 23 allows asubscriber to use phone 12 to originate or receive VoIP calls and invokeVoIP features. Typically, a Residential Gateway 23 provides an internalconfiguration webpage, accessible with a personal computer (not shown)to allow a subscriber to customize the operation of the ResidentialGateway 23.

The VoIP client supported by the Residential Gateway 23 is provisionedwith, or uses a discovery protocol such as DNS to learn, the address ofSSC 37, and the VoIP client authenticates and registers with SSC 37, byway of an SIP REGISTER message, to inform the SSC 37 of the “contactaddress” for the subscriber. As noted above, in this particulardisclosed embodiment, SIP is employed between SSC 37 and the VoIPclient. SIP is a signaling protocol for Internet conferencing,telephony, presence, events notification, instant messaging, and thelike. SIP uses a long-term stable identifier, the SIP Uniform ResourceIdentifier (URI) and the SIP URI scheme as presented in RFC 3261. SIPprotocol is employed to initiate and to modify a multimedia session overthe internet protocol (IP) network. SIP can be regarded as the enablerprotocol for VoIP services.

SIP is a text-based protocol and uses the UTF-8 character set. A SIPmessage is either a request from a client to a server, or a responsefrom a server to a client. Basic formats of both request and responsemessages are presented in RFC 2822. The Session Initiation Protocol(SIP) as described in RFC 3261 may be used as a VoIP signaling protocol.The VoIP clients are also referred to as “SIP clients.” As notedpreviously, the use of SIP is merely exemplary, and the VoIP client mayuse another VoIP telephony protocol.

In an example, the above network resources can be employed to provide asubscriber with an integrated cellular/wireline VoIP service by:

-   Uniquely assigning one of the “integration routing numbers” 38 to    the subscriber.-   Creating an FA group containing the subscriber's MDN as a pilot    number, and having the uniquely assigned “integration routing    number” as another member of the FA group.-   Providing the subscriber with a Residential Gateway for    installation,-   Provisioning a record for the subscriber in the SSC containing    relevant subscriber-specific information, such as the subscriber's    MDN, the assigned “integration routing number,” and information    corresponding to the Residential Gateway.

Then, SSC 37 operates, as detailed below, to employ the above featuresto provide an integrated cellular/wireline VoIP service.

When the SSC 37 receives an SIP INVITE initiating a new outbound callfrom the VoIP client, and the invite is addressed to a number (or to aSIP-URI or Tel-URI associated with the number), the SSC 37 acts as aBack-to-Back User Agent for the call, and extends a new call leg totoward the called number. The caller identification data (e.g., CallerID) for this new call leg includes the MDN of the subscriber's cellularphone. This allows calls placed from the subscriber's wireline VoIPphone 12 to other parties to be indistinguishable from calls placed fromthe subscriber's cellular phone. For all normal purposes, the subscriberis seen as having a single number, the subscriber's MDN; thesubscriber's “integration routing number” is, in normal circumstances,invisible to third parties

When SSC 37 receives an SIP INVITE for a new inbound call and the INVITEis addressed to a subscriber's “integration routing number” (or anassociated SIP-URI or Tel-URI), SSC 37 examines information received inthe INVITE for an encapsulated ISUP IAM. If the ISUP IAM is present, SSC37 examines the ISUP Calling Party Number, Original Called Number, andRedirecting Number parameters contained therein, if available, todetermine whether SSC 37 will either 1) reject the call, or 2) act as aBack-to-Back User Agent for the call and extend a new call leg towardthe subscriber's Residential Gateway 23, in which case the subscriber'swireline VoIP phone 12 can be used to answer the call.

More specifically, SSC 37 will normally reject the call if the INVITEdoes not contain an encapsulated IAM. Further, SSC 37 will normallyreject a call unless the ISUP Calling Party Number, Original CalledNumber, and Redirecting Number parameters are populated in a manner thatindicates that the inbound call either 1) originated from thesubscriber's cellular phone 11, or 2) began as a call to the FA grouppiloted by the subscriber's MDN. However, the SSC 37 will extend a newcall leg toward the subscriber's Residential Gateway 23 allowing it tobe answered by the subscriber's wireline VoIP phone 12 if the inboundcall 1) originated from the subscriber's cellular phone 11, or 2) is acall leg resulting from a call to the FA group having the subscriber'sMDN as pilot number.

For all normal purposes, the subscriber would be seen by others ashaving a single number, the subscriber's MDN, which would be used ascaller ID when the subscriber called them and that they would use toplace a call to the subscriber. Outside callers would be unaware ofwhich phone the subscriber used to answer their call, or even of thefact that the subscriber has both a cellular phone 11 and a wirelineVoIP phone 12. A subscriber would be call the subscriber's own wirelineVoIP phone 12 from the subscriber's own cellular phones 11 by callingthe subscriber's own “wireline integration number”. But the subscriber's“integration routing number” would, in normal circumstances, beinvisible to third parties; deliberate or accidental attempts by acaller to place a call directly to the wireline VoIP phone 12 by callingthe “integration routing number” would be rejected (although, as will bediscussed below, a limited exception may be made for call back callsassociated to emergency calls).

As mentioned above, the integration described above also extends tovoice mail services. As part of the normal handling of the FA feature byMSC 21 and HLR 39 controlling FA for the subscriber's FA group, if acall is not answered by a member of the FA group (i.e., subscriber'scellular phone 11 or wireline VoIP phone 12), MSC 21 will redirect thecall to the subscriber's cellular voice mail system 26. Moreover, theMSC 21 and HLR 39 will recognize (or can be configured or upgraded torecognize) a call to the pilot MDN from the subscriber's cell phone 11as a call that should be immediately routed to the subscriber's voicemail system 26. The subscriber's cellular phone 11 will work normally,retrieving voice mail messages by placing a call to its own MDN.Additionally, SSC 37, MSC 21, and HLR 39 will operate together so as toprovide similar accessibility to cellular voice mail system 26 from thewireline VoIP phone 12. Since the SSC 37 includes the MDN belonging tothe cell phone 11 as the caller identification data for calls placedfrom the wireline VoIP phone 12, just as that MDN is used as calleridentification for calls originating from the cellular phone 11, MSC 21and HLR 39 will not be able to distinguish between calls placed from thewireline VoIP phone 12 to the MDN and calls placed by the cell phone 11to the MDN. Consequently, a call placed from the wireline VoIP phone 12to the pilot MDN will be immediately routed to the subscriber's voicemail system 26, just as if the call had been placed from subscriber'scellular phone 11. The voice mail system 26 will also be unable todistinguish between such calls placed from the subscriber's wirelineVoIP phone 12 and such calls placed from the subscriber's cellular phone11, thereby providing ready voice mail access to the subscriber'svoicemail box in retrieval mode.

A service provider may choose to provide selected exceptions to thegeneral use of the subscriber's MDN as caller identification data forcalls placed from the wireline VoIP phone 12 as described above. Forexample, the subscriber may wish to place a call from wireline VoIPphone 12 to Mobile Station 11 without the call being automaticallydirected to voice mail system 26 for voice mail retrieval, as justdescribed. To permit this, the SSC 37 may be configured to recognizespecial dialing strings or dialing prefixes as a subscriber request notto use the subscriber's MDN in caller identification data. In suchexceptional circumstances, SSC 37 may omit caller identification data,or instead include the “integration routing number” in the calleridentification data.

A service provider may also choose to provide an exception to thegeneral use of the subscriber's MDN as caller identification data forcalls placed from the wireline VoIP phone 12 for emergency calls fromthe wireline VoIP phone 12 to public safety answering points (PSAPs),such as 911 calls in the US. If the MDN were provided as calleridentification data for an emergency call, a call back call from thePSAP to the subscriber might be answered by the cell phone, and neverreach the caller who placed the emergency call from the wireline VoIPphone 12. To prevent this from happening, the service provider mightconfigure the SSC 37 to use the subscriber's “routing integrationnumber” as caller identification data for emergency calls from thesubscriber's wireline VoIP phone 12. However, if the PSAP were to placea call back call to the subscriber's “roaming integration number,” thatcall would normally be blocked by the SSC 37 since the call signalingdoes not indicate to the SSC 37 that the incoming call is a call from anemergency service responder attempting to place a call back call for anemergency call previously placed by the wireline VoIP phone 12. Toensure that a call back call from a PSAP can reach the subscriber'swireline VoIP phone 12, if the service provider configures the SSC 37 touse the subscriber's “integration routing number” as calleridentification data for emergency calls placed from the subscriber'swireline VoIP phone 12, the service provider should also configure theSCC 37 to temporarily suspend incoming call screening for calls to thesubscriber's wireline VoIP phone 12 for a period of time following theend of an emergency call placed from the subscriber's wireline VOIPphone 12

Call Processing Examples:

A) Incoming Call from PSTN to Pilot Number

-   1) Phone 41 places call via PSTN 40 to the MDN. This call is routed    to MSC 21.-   2) Home MSC 21 for MS 11, which manages the FA Group, extends call    legs to MS 11 and the integration routing number assigned to VoIP    client 23.-   3a) In response to the call leg to MS 11, MS 11 rings, indicating an    incoming call-   3b) The call leg to the integration routing number is routed to MGW    25. MGW 25 sends a SIP INVITE to SSC 37. Via Internet 35, SSC 37    sends a SIP INVITE to VoIP Client 23. VoIP client 23 rings phone 12,    indicating an incoming call.-   4) Both MS 11 and phone 12 ring in response to the incoming call to    the pilot number.-   5) If the customer takes the call at either MS 11 or phone 12, the    connection is completed to the phone that took the call, and the    other call leg is terminated.-   6) If the call is not taken at either phone, MSC 21 terminates the    two call legs and extends a new call leg to voice mail 26 associated    with MS 11, which handles the incoming call in the conventional    manner.

B) Outbound Call from VoIP Client to Phone on PSTN (see FIG. 2)

-   1) On phone 12, customer dials number for phone 41, which is    accessible via PSTN 40. Attached VoIP client 23 sends a SIP INVITE    to SSC 37 via Internet 35 (step 201).-   2) SSC 37 sends a SIP INVITE to a MGW, such as MGW 25 (step 203).    Call origination data for the call leg is set to indicate that the    call originated from the MDN, rather than the integration routing    number assigned to VoIP client 23 (step 202).-   3) The MGW extends a call leg, via PSTN 40, to phone 41 (step 204).

C) Call from Mobile Station to VoIP Client

-   1) Call is placed from MS 11 to the integration routing number    assigned to VoIP client 23.-   2) The call is routed to MGW 25, which sends a SIP INVITE to SSC 37.-   3) SSC 37, which ordinarily would not accept a call made directly to    the integration routing number, recognizes that the call originated    from MS 11 associated with the pilot number for the FA Group. SSC 37    sends a SIP INVITE to VoIP client 23.-   4) VoIP client 23 receives the SIP INVITE, and rings phone 12, at    which the call placed from MS 11 can be received.

D) Call from VoIP Client to Mobile Station (see FIG. 3)

-   1) On phone 12, customer dials a string of digits to indicate that    the outbound call is not to use the pilot number as caller    identification data. This string of digits is followed by the number    for MS 11 (i.e., the FA Group pilot number) (step 301). Attached    VoIP Client 23 sends an SIP invite to SSC 37 via Internet 35 (step    302).-   2) SSC 37 extends a call leg to MS 11 (step 304). Call origination    data is set to indicate the integration routing number as where the    call originated from, rather than using the MDN (step 303). Thus,    when MS 11 receives the call, it will be apparent that the call    originated at the customer's residential phone 12.-   3) The call leg is routed to MS 11 (step 305).

D) Emergency services call from VoIP Client (see FIG. 4)

-   1) On phone 12, customer dials an emergency services call (e.g., a    911 call in the US) and phone 12 sends a SIP INVITE via the Internet    to the SSC 37 (step 401).-   2) SCC 37 recognizes the call as an emergency call; starts an    incoming call screening suspension timer (step 402); sets the caller    identification for the call to the subscriber's integration routing    number (step 403); and extends a call leg (step 404).-   3) The call leg is routed to the PSAP (step 405).-   4) The PSAP initiates a call back call to the subscriber's    integration routing number (step 406)-   5) The SSC 37 receives the incoming SIP INVITE for the call back    call (step 407).-   6) If the incoming call screening suspension timer is still running    (step 408), the SSC 37 forwards a call leg toward the phone 12 (step    409).

Aspects of the methods outlined above may be embodied in programming,e.g. in the form of software, firmware, or microcode executable by aserver or other programmable device. Such programming typically iscarried on or otherwise embodied in a medium or media. Terms such as“machine-readable” medium and “computer-readable” medium as used hereingenerically refer to any tangible medium that participates in providinginstructions and/or data to a programmable processor, such as the CPU orother processor of a server computer or user terminal device, forexecution or other processing, including both storage media andcommunication media. A medium may take many forms, including but notlimited to, non-volatile storage media and volatile storage media.Non-volatile storage media include, for example, optical or magneticdisks and flash memory. Volatile storage media include dynamic memory,such as main memory or cache. Hence, common forms of machine-readablestorage media include, for example, a floppy disk, a flexible disk, ahard disk, a magnetic tape, any other magnetic medium, a CD or CDROM, aDVD or DVD-ROM, any other optical medium, punch cards, paper tape, anyother physical medium with patterns of holes, a RAM, a PROM, an EPROM,an EEPROM, a FLASH-EPROM, a cache memory, or any other memory chip orcartridge.

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that the teachings may beapplied in numerous applications, only some of which have been describedherein. It is intended by the following claims to claim any and allapplications, modifications and variations that fall within the truescope of the present teachings.

What is claimed is:
 1. An article of manufacture, comprising anon-transitory computer-readable medium and computer-executableinstructions embodied in the medium that, if executed by a processor,cause the processor to perform functions, including functions to: inresponse to an inbound call received on a cellular communication networkand placed to a first pilot telephone number identifying a first groupof telephone numbers of a plurality of groups of telephone numbers,initiate a first inbound call leg to a cellular telephone to which thefirst pilot telephone number is assigned and a second inbound call legto a first telephone number associated with a Voice over InternetProtocol (VoIP) client, wherein: the first pilot telephone number is amobile directory number of the cellular telephone, and the first groupof telephone numbers includes at least the first pilot telephone numberand the first telephone number associated with the VoIP client;automatically route to a voice mail system for voice mail retrieval afirst outbound call for the cellular telephone from the VoIP clientbelonging to the first group of telephone numbers; and establish asecond outbound call from the VoIP client to the cellular telephone,without the second outbound call being automatically directed to thevoice mail system, in response to input of a special dial string at theVoIP client.
 2. The article of manufacture of claim 1, wherein thefunctions further include a function to establish an outbound call withcaller identification data set to correspond to the mobile directorynumber in response to an outbound call originated by the VoIP client sothat the outbound call originated by the VoIP client appears as anoutbound call by the mobile directory number.
 3. The article ofmanufacture of claim 1, wherein the functions further include a functionto establish an inbound call to the VoIP client via the second inboundcall leg to the first telephone number.
 4. The article of manufacture ofclaim 1, wherein the functions further include a function to establishan outbound call leg with caller identification data set to correspondto the first pilot telephone number in response to an outbound calloriginated by the cellular telephone.
 5. The article of manufacture ofclaim 1, wherein the functions further include a function to establishan inbound call to the VoIP client in response to an inbound call placedto the first telephone number from the cellular telephone.
 6. Thearticle of manufacture of claim 1, wherein the functions further includea function to refuse to establish an inbound call to the VoIP client ifthe inbound call lacks caller identification data.
 7. The article ofmanufacture of claim 1, wherein the functions further include a functionto refuse to establish an inbound call to the VoIP client in response toan inbound call placed to the first telephone number if the inbound callhas caller identification data indicating that the inbound call wasneither: a call routed to the first telephone number by a flexiblealerting system, nor a call placed to the first telephone number fromthe cellular telephone.
 8. The article of manufacture of claim 1,wherein the special dial string at the VoIP client is not related to acalling feature for voice mail retrieval.
 9. The article of manufactureof claim 1, wherein a particular outbound call originated by the VoIPclient is established with caller identification data set to correspondto the mobile directory number of the cellular telephone so that theparticular outbound call originated by the VoIP client appears as anoutbound call by the mobile directory number of the cellular telephoneunless the special dial string is used at the VoIP client.
 10. Thearticle of manufacture of claim 1, wherein the functions further includea function to establish a particular outbound call originated by theVoIP client with caller identification data set to correspond to thefirst telephone number associated with the VoIP client, when theparticular outbound call is an emergency call placed by the VoIP client.11. The article of manufacture of claim 7, wherein the functions furtherinclude a function to suspend refusing to establish an inbound call tothe VoIP client for a period of time following the end of an emergencycall placed by the VoIP client.
 12. A system comprising: a Voice overInternet Protocol (VoIP) server configured to establish an inbound callto a VoIP client; and a mobile switching center of a cellularcommunication network, configured to route a first inbound call leg to amobile directory number of a cellular telephone and a second inboundcall leg to a telephone number associated with the VoIP client via theVoIP server, wherein: the mobile directory number of a cellulartelephone is a first pilot telephone number identifying a first group oftelephone numbers of a plurality of groups of telephone numbers, thefirst group includes at least the first pilot telephone number and thetelephone number associated with the VoIP client; and the VoIP server isfurther configured to: automatically route to a voice mail system forvoice mail retrieval a first outbound call from the VoIP client to thefirst pilot telephone number; and establish a second outbound call fromthe VoIP client to the first pilot telephone number, without the secondoutbound call automatically directed to the voice mail system, inresponse to an input at the VoIP client.
 13. The system of claim 12,wherein the VoIP server is further configured to: establish an inboundcall to the VoIP client in response to the second inbound call legrouted to the telephone number associated with the VoIP client; andestablish an outbound call with caller identification data set tocorrespond to the first pilot telephone number in response to anoutbound call originated by the VoIP client so that the outbound calloriginated by the VoIP client appears as an outbound call by thecellular telephone.
 14. The system of claim 12, wherein the VoIP serveris further configured to refuse to establish an inbound call to the VoIPclient if the inbound call lacks caller identification data.
 15. Thesystem of claim 12, wherein the VoIP server is further configured torefuse to establish an inbound call to the VoIP client in response to aninbound call placed to the telephone number associated with the VoIPclient, if the inbound call has caller identification data indicatingthat the inbound call was neither: a call routed to the telephone numberby the mobile switching center, nor a call placed to the telephonenumber from the cellular telephone.
 16. The system of claim 15, whereinthe VoIP server is further configured to suspend refusing to establishan inbound call to the VoIP client for a period of time following theend of an emergency call placed by the VoIP client.
 17. The system ofclaim 12, wherein the input at the VoIP client is not related to acalling feature for voice mail retrieval.
 18. The system of claim 12,wherein a particular outbound call originated by the VoIP client isestablished with caller identification data set to correspond to themobile directory number of the cellular telephone so that the particularoutbound call originated by the VoIP client appears as an outbound callby the mobile directory number of the cellular telephone unless theinput indicates to not use the mobile directory number as the calleridentification.
 19. The system of claim 12, wherein a particularoutbound call originated by the VoIP client is established with calleridentification data set to correspond to the telephone number associatedwith the VoIP client, when the particular outbound call is an emergencycall placed by the VoIP client.